A dichotomous key is developed which provides the investigator a means for identifying the common marine molluscs on the Texas coast. The key is written as to allow the user to stop or begin at any desired taxonomic level (class, order, superfamily, family, genus, species) depending on prior knowledge or specific need (Table 1). Because of the special importance of bivalves to many studies, species-specific information is provided pertaining to feeding type, relation to substrate, and distribution (Table 2). An illustrated glossary is also provided.